A highway-rail grade crossing warning system is typically comprised of a train detection system, coupled with a crossing control system to provide appropriate warning to the road users, usually by means of flashing lights, barrier gates and bells. Recorders are also typically deployed to monitor the train detection and crossing control equipment. Such recorders are also of assistance in incident investigation and in equipment troubleshooting.
A track circuit based upon closed circuit fail-safe design principles is used to detect trains approaching a crossing. An interruption or disturbance in the circuitry or in the signals impressed on the rails to detect trains will activate the crossing warning devices. This track circuit is defined by the placement of special shunts at the end of the track circuit approach, and by the location of transmit and receive wires attached to the track, typically at the crossing. However, for certain remote applications there may not be a physical crossing.
Track circuits may be either unidirectional or bi-directional. A special section of the track circuit that typically encompasses the highway-rail intersection is called the island circuit. This is usually defined by the area between transmit and receive leads for the track circuit for the entire approach. The same track leads are used for the island and the approach, although different signals are used.
Current industry practice for troubleshooting and calibrating electronic highway grade crossing equipment track circuits and flashing warning light voltages is to employ two people. One person is typically located on the track circuit or near the light circuits, and the second person is typically located near the equipment to control and monitor the track circuit and to adjust the output to the warning lights. The first person will typically be placing shunting wires on the track circuit or measuring light voltages. The second person will typically interact with the equipment to initiate calibration or setup procedures, as well as to record certain system parameters. These two people typically interact by means of standard VHF two-way radio handsets, by cell phones or by other two-way communication devices since approaches can be on the order of 4500 feet or more.
Many of the calibration and troubleshooting track circuit functions require shunts to be placed on the track prior to starting the calibration or troubleshooting procedures. Thus, coordination between the two persons is of key importance. VHF handsets are typically standard issue for railroad maintenance staff. In certain cases only one person may be available. If so, this means that the single person has to make multiple trips out to place shunts on the track and then return to the equipment to perform the calibration or troubleshooting procedures. This also means that the maintenance procedures can take a significantly longer time as compared to the use of two persons. Most track calibration or other maintenance procedures also require that protected track time be obtained from dispatchers. That is, no trains are allowed on the track during such maintenance procedures. Thus, minimizing the time to perform these maintenance procedures is of great benefit to the railroad. It is also of benefit to the road user, and helps the credibility of the crossing.
A general object of the present invention is to emulate the role of a second person while performing maintenance or troubleshooting procedures so that these procedures can be effectively performed by a single person.
Another object of the present invention is to provide for significant time savings as compared to a single person attempting to perform maintenance or trouble shooting procedures without use of the present invention.
A further object of the present invention is to provide closed-loop, fail-safe controls to insure that only the intended crossing is affected by the intended procedures.
Yet another object of the present invention is to provide for more efficient maintenance and troubleshooting procedures that are compatible with existing equipment, such as VHF communication device handsets.